Finite element modeling of fixture?workpiece contacts: single contact modeling and experimental verification

Abstract

Knowledge of workpiece elastic deformation and reaction forces are essential for machining surface error prediction and stability analysis of the fixture–workpiece system. A finite element (FE) model of the fixture–workpiece system is well-suited for predicting workpiece elastic deformation and reaction forces as it can easily account for all sources of compliance in the system. However, the reaction forces and workpiece elastic deformations predicted by the FE model are known to be very sensitive to the boundary conditions used to model the fixture–workpiece contact interface. In this paper, the effects of different FE boundary conditions on the deformation and reaction force predictions for a single fixture–workpiece contact are analyzed. Specifically, frictional contact elements, and nodal force and displacement boundary conditions applied to spherical–planar and planar–planar locator and clamp contact geometries are considered. The effects of workpiece compliance on the prediction accuracy are also evaluated. Based on this study, specific guidelines for FE modeling of locator–workpiece/clamp–workpiece contacts are developed and verified through experiments.